Declarative UI Development with Qt Quick

Qt 4.7 introduces Qt Quick, the Qt UI Creation Kit. that enables the creation of dynamic user interfaces, easier and more effective than possible with existing UI technologies. This UI Creation Kit consists of three technologies:

QML is a declarative language oriented on JavaScript that utilizes Qt's Meta-Object capabilities to enable designers and developers to collaborate tightly and create animated and fluid user experiences, using existing knowledge in script language and design.

Qt Declarative is a C++ library that provides the underlying engine, which translates the declarative description of the UI in QML into items on a QGraphicsScene. The library also provides APIs to bind custom C++ types and elements to QML, and to connect the QML UI with the underlying application logic written in C++.

Qt Creator has been improved to support interactive editing of QML UIs through drag-and-drop. The text editor supports the QML syntax and provides authoring assistance such as auto-completion, error lookup, help lookup and easy preview of QML UI's. The Qt Quick features in Qt Creator will be released with Qt Creator 2.1

Network Bearer Management

Bearer Management controls the connectivity state of the system. The new Bearer Management API in the QtNetwork module allows the application to identify whether the system is online and how many interfaces there are, as well as start and stop interfaces, or roam transparently between access points.

On mobile platforms, it is often useful to avoid displaying separate scrollbars for iframes and framesets. If you switch on frame flattening, QtWebKit will resize frames to fit their content to avoid separate scrollbars (see QWebSettings::FrameFlatteningEnabled).

Qt 4.7 adds support for accelerated compositing, which enhances the performance of CSS animations and transitions. Read more in this blog.

For hybrid QtWebKit and C++ projects, Qt 4.7 has added support for transporting QPixmaps between Qt C++ and WebKit. We have also improved the documentation for hybrid development. Read more here: The QtWebKit Bridge.

QtWebKit Performance Benchmarks

We have introduced a set of performance benchmarks for QtWebKit, and made numerous improvements in rendering performance, page loading performance, scrolling performance and CSS performance. Here are some examples from the benchmarks run on a 64-bit Linux workstation with the raster graphics system.

In a benchmark that measures the scrolling performance on popular websites, we found out that Qt 4.7.0 on this platform is 350% faster than Qt 4.6.0, thanks to several rendering related improvements.

Our page loading benchmark shows an improvement of 16% in Qt 4.7.0 from Qt 4.6.0. This is due to improvements in text layout speed, image decoding, resource loading and event handling.

Several CSS animation benchmarks indicate a speed improvement of 31% from Qt 4.6.0 to Qt 4.7.0. These benchmarks are effectively showing the improvement we get from accelerated compositing (see above).

Other Performance Related Improvements

In addition to the QtWebKit module, performance has been a focus area in Qt 4.7 throughout the Qt framework. Here are a couple of examples about performance related feature improvements.

On Mac OS X, Qt now uses a different widget implementation (called "alien widgets"), which improves the responsiveness of applications that have complex user interfaces with several widgets.

Qt 4.7 introduces the QStaticText class, which can be used to improve text rendering performance. More info is available from this blog.

The QPainter class has a new API for rendering pixmap fragments (QPainter::drawPixmapFragments), which can improve the rendering performance of applications that need to render pixmap fragments.

Qt 4.7 has an updated version of the JavaScriptCore engine for the QtScript module, which improves JavaScript execution performance.

New Classes, Functions, Macros, etc.

Links to new classes, elements, functions, macros, and other items introduced in Qt 4.7.

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